1. Field of the Invention
This invention relates to a scoring device and more particularly to a scoring device having a referencing carriage to maintain a constant predetermined scoring force or scoring load on a scoring wheel.
2. Discussion of the Prior Art and Technical Problems
In the prior art, there is taught the use of spiraled, coiled springs for applying a load or force on a scoring wheel. Such teachings are found in U.S. Pat. Nos. 1,167,254; 3,240,090; 3,280,676; 3,280,677; 3,577,636; and 3,807,261 to name a few.
Although the use of spiraled, coiled springs for applying a scoring force on a scoring wheel is acceptable, there are drawbacks. For example, coiled and tension springs are adjusted to apply a predetermined force on the scoring wheel to score a glass ribbon. As the glass ribbon advances along a conveyor past the scoring wheel, the scoring wheel pivots toward and away from the conveyor. The movement of the scoring wheel may be the result of eccentric conveyor rolls that advance the glass ribbon or variations in glass thickness. When the scoring wheel moves away from the conveyor, coiled springs compress and tension springs expand thereby increasing the scoring force acting on the scoring wheel. Further, when the scoring wheel moves toward the conveyor, coiled springs expand and tension springs compress to decrease the scoring force acting on the scoring wheel.
In the scoring of glass sheets, in particular glass sheets having a thickness of less than about 1/8 inch (0.32 centimeter), variations in the scoring force give inconsistent scores. For example, if the force acting on the scoring wheel is too high, e.g., above about 10 pounds (4.5 kilograms), the glass surface may be crushed at the score line. Conversely, if the scoring force acting on the scoring wheel is too low, e.g., below about 3 pounds (1.35 kilograms), the score is too shallow.
U.S. patent application Ser. No. 669,560 filed on Mar. 23, 1976, in the name of R. M. Bonaddio for a "Force Applying Device for Scoring Wheels" eliminates the above drawbacks of the prior art. As taught in the above-mentioned U.S. patent application, a constant force coil spring biases an end of a lever arm. A scoring wheel mounted on the other end of the lever arm is thereby urged against a piece of glass.
The scoring device taught in U.S. patent application Ser. No. 669,560 is suitable to eliminate force variations applied to a scoring wheel. It would be advantageous to have still another type of scoring device that has facilities for maintaining a constant, predetermined load on the scoring wheel during scoring of a glass ribbon.